Researchers at the University of Adelaide's School of Medical Sciences have identified a link between SIDS and breathing problems, finding that telltale signs in the brains of babies who died of SIDS are remarkably similar to those of children who died of accidental asphyxiation.

SIDS also known as cot death or crib death is the sudden death of an infant that is not predicted by medical history and remains unexplained after a thorough forensic autopsy and detailed death scene investigation.

"This is a very important result. It helps to show that asphyxia rather than infection or trauma is more likely to be involved in SIDS deaths," project leader Roger Byard said.

The study compared 176 children who died from head trauma, infection, drowning, asphyxia and SIDS.

Researchers were looking at the presence and distribution of a protein called ß-amyloid precursor protein (APP) in the brain. The "APP staining" technique, as it is known, could be an important tool for showing how children have died. This is the first time a detailed study of APP has been undertaken in SIDS cases.

"All 48 of the SIDS deaths we looked at showed APP staining in the brain," Byard said. "The staining by itself does not necessarily tell us the cause of death, but it can help to clarify the mechanism," he added.

"The really interesting point is that the pattern of APP staining in SIDS cases - both the amount and distribution of the staining - was very similar to those in children who died from asphyxia," Byard said.

He said that in one case, the presence of APP staining in a baby who had died of SIDS led to the identification of a significant sleep breathing problem, or apnoea, in the deceased baby's sibling.

"This raised the possibility of an inherited sleep apnoea problem, and this knowledge could be enough to help save a child's life," he said.

"Because of the remarkable similarity in SIDS and asphyxia cases, the question is now: is there an asphyxia-based mechanism of death in SIDS? We don't know the answer to that yet, but it looks very promising."

The study was by visiting postdoctoral researcher Lisbeth Jensen from Aarhus University Hospital, Denmark.

"This work also fits in very well with collaborative research that is currently being undertaken between the University of Adelaide and Harvard University, on chemical changes in parts of the brain that control breathing," Byard said.